The diagram below shows a small water heater that uses electrical energy to heat water. The heating element is a small resistor labeled Rjoad = 5.0 0 immersed in the water. A 20 V ideal emf device supplies current and there is an adjustable resistor Ra in series. The value of the adjustable resistance can be changed to be anywhere between 1.0 - 3.0 N. The adjustable resistor is initially set to 2.0 N and the switch is closed. (a) What is the voltage drop across the heating element? (b) How much energy is supplied by the source if the water heater runs for 10 minutes? (c) What fraction of this energy is actually used to heat the water? Please express your answer percentage, using only two significant figures. (d) Suppose the heating element degrades and corrodes and its resistivity slowly increases as the equip- a ment becomes older. • Does the voltage drop across the heating element increase, decrease or remain the same as the equipment gets older? • Does the the total power consumed by the circuit increase, decrease or remain the same as the equipment gets older? R = 5.0 2 R. 1-3.0 2 E320.0 V fww

The diagram below shows a small water heater that uses electrical energy to heat water. The heating element is a small resistor labeled Rjoad = 5.0 0 immersed in the water. A 20 V ideal emf device supplies current and there is an adjustable resistor Ra in series. The value of the adjustable resistance can be changed to be anywhere between 1.0 - 3.0 N. The adjustable resistor is initially set to 2.0 N and the switch is closed. (a) What is the voltage drop across the heating element? (b) How much energy is supplied by the source if the water heater runs for 10 minutes? (c) What fraction of this energy is actually used to heat the water? Please express your answer percentage, using only two significant figures. (d) Suppose the heating element degrades and corrodes and its resistivity slowly increases as the equip- a ment becomes older. • Does the voltage drop across the heating element increase, decrease or remain the same as the equipment gets older? • Does the the total power consumed by the circuit increase, decrease or remain the same as the equipment gets older? R = 5.0 2 R. 1-3.0 2 E320.0 V fww

University Physics Volume 2

18th Edition

ISBN:9781938168161

Author:OpenStax

Publisher:OpenStax

Chapter9: Current And Resistance

Section: Chapter Questions

Problem 84CP: In this chapter, most examples and problems involved direct current (DC). DC circuits have the...

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